An electronic apparatus generally includes an enclosure to define a closed inner space, within which a plurality of different electronic elements work for the electronic apparatus to operate. These electronic elements produce heat during work. Therefore, elements capable of dissipating heat produced by the electronic elements must be additionally provided in the electronic apparatus to help in cooling the heat-producing electronic elements. Heat sink is one example of such heat dissipating elements to assist in quick dissipation of heat. The conventional heat sink is normally made of a metal material having high heat conductivity. In the past, a big-scale heat sink is manufactured by integral molding through casting or forging. To manufacture the heat sink by casting or forging, it is necessary to develop a big-size mold, which is not only heavy and inconvenient to manufacture and transport, but also expensive and non-economic for use.
Please refer to FIGS. 1 and 2. In a conventional technique for providing a heat sink 1 by way of extruding an aluminum material, the heat sink 1 is assembled from a plurality of modular heat radiating units 11. Each of the heat radiating units 11 is formed on a first plane 111, say, a top surface, along each of two longitudinal edges with two parallelly extended arms 1111, and on a second plane 112 opposite to the first plane 111 with a V-shaped groove 1112 corresponding to the two arms 1111. To stack and assemble two modular heat radiating units 11 together, the parallel arms 1111 on a lower one of the two units 11 are forced into the V-shaped grooves 1112 on an upper one of the two units 11. At this point, the parallel arms 1111 are deformed corresponding to the configuration of the V-shaped grooves 1112, so that the two modular heat radiating units 11 are connected to each other. Other modular heat radiating units 11 may be sequentially stacked in the same manner. With the heat sink 1, the problem of heavy and expensive mold for casting or forging a big-scale heat sink is solved. However, the heat sink 1 has some disadvantages in practical use thereof. When the arms 1111 are forced into the V-shaped grooves 1112 and deformed, stress concentration will occur at a neck portion of the arms 1111 in contact with the first plane 111. As a result, two modular heat radiating units 11 that have been connected to each other through engagement of the arms 1111 with the V-shaped grooves 1112 are still subject to separation due to broken arms 1111. Further, it is also possible the arms 1111 are not smoothly and fully forced into the V-shaped grooves 1112, and two modular heat radiating units 11 are not fully closely attached to each other. That is, there might be voids between the arms 1111 and the V-shaped grooves 1112 to cause thermal choking. Moreover, since the arms 1111 are deformed under external force, they are not repeatedly usable.
In brief, the conventional heat sink 1 with modular heat radiating units 11 has the following disadvantages: (1) the modular heat radiating units have a connecting structure that is subject to breaking to thereby cause separation of two assembled modular heat radiating units from one another; (2) the modular heat radiating units could not be fully tightly connected and closely attached to one another to thereby cause thermal choking between them; (3) stress concentration tends to occur at deformed areas on the modular heat radiating units; (4) the modular heat radiating units have poor structural strength; and (5) the modular heat radiating units are not repeatedly usable.
It is therefore tried by the inventor to develop a heat radiating unit structure and a heat sink thereof to overcome the problems in the conventional heat sink with modular heat radiating units.